Conventionally, turbines such as steam turbines and gas turbines, which rotate their rotating shaft to generate power by expansion of high-temperature operating fluid inside a casing that encases a blade structure therein, have found wide applications in various fields. Various rotating machines other than such turbines have also been used. Bearing devices are essential in such rotating machines for supporting the rotating shaft, and typically lubricating oil is supplied to the inside of the bearing devices.
The bearing device is provided with a mechanism for preventing oil leakage so that lubricating oil does not leak to the outside of the bearing box. This is because oil leakage causes consumption of much lubricating oil inside the bearing box and also causes a stain or the like around the bearing device. An oil leakage prevention mechanism may include, for example as shown in Patent Literature 1, an oil thrower between the bearing box and the rotating shaft. The bearing device is known, for example, as disclosed in Patent Literature 2. A mechanical seal for a shaft is known, for example, as disclosed in Patent Literature 3.    [Patent Literature 1] Japanese Patent Application Laid-Open No. H11-62888 (Paragraph [0002] and FIGS. 3 and 4)    [Patent Literature 2] Japanese Patent Application Laid-Open No. H9-229069    [Patent Literature 3] Japanese Patent Application Laid-Open No. H5-71647